Storing more data in a storage device is desired. Means using the storage device whose capacity is large can increase a quantity of data storable in the storage device. On the other hand, if the storage device having a large storage capacity is large in size and expensive, it sometimes does not meet needs of a user. For this reason, as a technique of storing more data in the storage device without increasing a size of the storage device, a technique of compressing data is provided.
The reference literature 1 (WO 2012/124100 A1) discloses a technique in which, when writing data in the storage device, a process taking shorter processing time, which is selected out of a process of compressing writing-target data and then writing the data in the storage device and a process of writing data in the storage device without compressing the data, is performed to write the data.